1. Field of the Invention
This invention relates generally to locks, and more specifically, to locks used to prevent theft of spare tires.
2. Prior Art
Spare tire theft continues to pose a problem to new pickup truck dealers. GM pickup trucks utilize a hoist mechanism to secure the spare tire underneath the rear of the pickup truck. The hoist has a shaft that rotates to raise and lower the spare tire. This convenience makes it easy for thieves to quickly lower and remove the spare tire from the truck while the truck is parked on the dealer lot. To prevent the theft of spare tires GM Truck dealers install spare tire locks on their pickup trucks. The largest dealers install hundreds of spare tire locks each year.
Because such a large number of locks are installed, it is desirable to have a lock that can be quickly installed and extremely difficult to defeat. Even a relatively low defeat rate can lead to substantial spare tire loss over time.
In the past, various devices have been proposed in an attempt to solve the problem of spare tire theft. One device is disclosed in U.S. Pat. No. 4,526,021 to Princell. The Princell device is installed on the end of the hoist shaft to prevent the spare tire from being lowered. This device has two brackets; one bracket fits inside the end of the hoist shaft, with the other bracket fitting over the hoist shaft and butting up against a stationary member. Each of the brackets has a flat portion with holes that align so that the shackle of a padlock can pass through the holes.
A second device is shown in U.S. Pat. No. 5,199,278 to McClary. It is also installed over the end of the hoist shaft to prevent lowering of the spare tire. This device has a cup that fits over the end of the hoist shaft with a locking shaft extending from the cup and through an opening in the bumper. A padlock is then placed through a hole in the locking shaft to prevent removal.
Each of these devices may be well suited for the particular application for which they were designed. However, their ability to be adapted to other applications is limited. The Princell device is well suited for use on pickup trucks having a stationary member for the bracket that fits over the hoist shaft to butt up against. However, this device is not effective on GM tracks because there is not a stationary member for the bracket to butt up against. The McClary device cannot be used on pickup trucks that do not have rear bumpers. Truck dealers often receive trucks with no rear bumper, so they would not be able to use the McClary device.
Another type of spare tire lock that is well suited for the hoist application is disclosed in U.S. Pat. No. 4,794,771 to Princell. This Princell device has a yoke that is saddled over the hoist haft after the spare tire has been lowered. Then, a shaft with a specially shaped tab at the end is placed through holes in the yoke and rotated downward. The shaft has a bend approximately forty-five degrees near the end with the tab allowing the shaft to hang vertically when rotated downward. Once the device is in final position and the spare tire has been raised the shaft protrudes through a lug hole. A lock is then slid up onto the shaft to prevent spare tire removal. However, this device has several drawbacks. The method necessary to install this device is cumbersome and time consuming. Installation of this device requires the spare tire to be lowered and then raised to install. Also, the use of the yoke and specially shaped tab portion at the end of the shaft makes assembly more difficult than is necessary.
In summary, the prior devices do not meet the needs of track dealers. The devices do not have the flexibility to fit all hoist applications and contain unnecessary components and steps to install.
It is therefore an object of the present invention to provide a spare tire lock with an improved design and method of installation. In addition the present invention provides a spare tire lock with the flexibility to fit all hoist applications.